1. Field of the Invention
The present invention relates to systems for generating tension in the endless track of a tracked work machine.
2. Description of Related Art
Tracked work machines are a staple in the military, construction, agriculture, mining, lumber, and other heavy industries. Tracked work machines range in shape and size from tanks and bulldozers to backhoes, mobile cranes, snowmobiles, and robots. These machines are prized for their superior maneuverability over rough terrain, enabled primarily by their tracked means of movement.
Such work machines generally comprise a main frame or chassis, an engine or motor, a drive mechanism, and a tension management system. The frame or chassis is the main frame of the machine, upon which the other components are directly or indirectly mounted. For example, the engine or motor is mounted to the main frame. The drive mechanism comprises a drive mechanism frame coupled to the main frame, a drive wheel, an endless track, and a set of rollers or wheels. Two drive mechanisms are typically employed in a tracked work machine, one on each side of the machine.
The drive wheel is driven by the engine or motor. The drive wheel is in operative communication with an endless track. Further, the rollers or wheels are distributed along the drive mechanism frame over which the endless track passes. The rollers and drive wheel are distributed to define the path for the endless track to follow. The engine or motor generates rotation of the drive wheel, which in turn results in complimentary rotation of the endless track.
Maintaining proper tension of the endless track is necessary for the proper operation of the work machine. If the tension is too low the endless track may buckle, slip off the drive wheel and rollers, jump between teeth on a sprocket drive wheel or roller, or not generate enough friction with the drive wheel to allow for rotation. Alternatively, if the tension is too high, premature wear may occur in components of the drive mechanism.
It is also important for the tension to be readily adjustable to prevent damage caused by debris passing between the endless track, and drive wheels, and rollers. Proper tension is also necessary for maintaining balance and stability during uphill or downhill movement, and during digging or other operations.
The tension management system of the tracked work machine maintains tension in the endless track of the drive mechanism. The tension management system comprises an idler wheel, a biasing element, and intermediary components for translating force from the biasing element to the idler wheel. The idler wheel is coupled to the drive mechanism frame in a manner that enables its position to be adjusted, which provides regulation for the tension in the endless track. The idler wheel is coupled to the biasing element, which generates force and adjusts the idler wheel's position. The biasing element presses the idler wheel against the endless track to increase tension in the endless track. The biasing element also actively or passively enables the idler wheel to ease away from the endless track to reduce tension in the track.
The large size and heavy loads of work machines require relatively high tension in the endless tracks. The connection between the biasing element and the idler wheel of the tension management system in conventional tension management systems is directly linear. FIG. 1 illustrates such conventional systems wherein a biasing element 10 is directly connected to a swing link 20. The force from the biasing element is translated in a linear manner. Examples of such arrangements of the idler wheel and biasing element in the prior art can be found in U.S. Pat. No. 7,172,257 to Tamaru et al. and U.S. Pat. No. 5,851,058 to Humbek et al. The biasing element in such conventional work machines is often a hydraulic or pneumatic pump or a set of powerful springs. Such elements are expensive and prone to frequent damage, necessitating repair or replacement due to the extreme forces being generated.
Until now, there has existed a need for a tension management system that can maintain proper tension in an endless track using a lightweight, less expensive biasing element than currently known. It is to such a tension management system that the present invention is primarily directed.